An AC input/DC output power supply employing a commercial power source as input has been widely used. Of such a power supply, improvement has been continuously attempted from various viewpoints. For example, Patent Literature 1 (PTL 1) discloses a technique for increasing efficiency and reducing power consumption. Patent Literature 2 (PTL 2) discloses a technique for preventing breakdown of an electrolytic capacitor. Patent Literature 3 (PTL 3) discloses a technique for improving output voltage accuracy. Patent Literature 4 (PTL 4) discloses a technique for noise reduction.
Most of electric and electronic devices using such power supplies are operated with a clock signal. For a reference vibration generation means for such a clock signal, a quartz resonator, a ceramic resonator or the like is used in most cases, but their accuracy is not so high. In view of that, there has been proposed a method of using a commercial power source frequency, which has high frequency accuracy. A commercial AC power source has a long-term frequency deviation of about 0.167 ppm, which corresponds to an accuracy of more than 30 times that of a generally used quartz resonator. For example, Patent Literature 5 (PTL 5) discloses a technique of a timer device where correction of a timing counter is performed using a commercial power source frequency. Further, Patent Literature 6 (PTL 6) discloses a technique of a pulse generator which generates a pulse whose frequency is an integral multiple of a commercial power frequency, using a PLL (Phase Locked Loop) circuit.
Using an AC input/DC output power supply and a clock generator such as the ones described above, both a DC voltage and a clock signal can be supplied to an electric or electronic device.
Further, also Patent Literature 7 (PTL 7) and Patent Literature 8 (PTL 8) each disclose a related technique.